Request: Add compatiblity with ONNX (OnnxStableDiffusionPipeline)

[n00mkrad]

Would be really great to get a speedup on DirectML/ONNX pipelines from Diffusers.

E.g. OnnxStableDiffusionPipeline, OnnxStableDiffusionImg2ImgPipeline, OnnxStableDiffusionInpaintPipeline.

[dbolya]

I'm not familiar with ONNX. What are the main differences with regular pytorch? If it's easy to do, I can write a patch.

[NatanBagrov]

Hi @dbolya, @n00mkrad ,
I've implemented an ONNX friendly counterpart :)
Let me know how that works for you